Personal computers — and the companies that make their crucial components — are about to go through their biggest upheaval since the rise of the laptop. By the end of the year, consumers are likely to see laptops the size of thin paperback books that can run all day on a single charge and are equipped with touch screens or slide-out keyboards.<img src="http://feeds2.feedburner.com/~r/digg/news/container/technology/popular/~4/fhIA0jVJOVo" height="1" width="1"/>